Flexible hoses



July 30, 1957 A.- a. HERON 2,801,323

FLEXIBLE HOSES Filed May 26, 1955 United States Patent FLEXIBLE HOSESAndrew George Heron, Benton, Newcastle upon Tyne, England ApplicationMay 26, 1955, Serial No. 511,333

5. Claims. (Cl. 21939) This invention relates to flexible hoses and isan improvement in or modification of the invention claimed in my patentapplication No. 12422/53.

In the form of hose described in the parent specification comprising twocoaxial braided wire conductors insulated fromone another, in the eventof any fault arising in the insulation, the risk of leakage between thetwo conductors extends throughout the area of the conductors, that is tosay the length of the hose multiplied by the circumference of thebraided wire conductors.

The main object of the invention is to provide a form of such twinconductor heating hose in which the potential fault area issubstantially reduced. Another object is at the same time to provide amethod of manufacture of the hose which will substantially reduce therisk of breakdown of the insulation.

According to the invention the one conductor consists in a lineconductor of compacted cross section which extends longitudinally alongthe wall of the hose.

Preferably the line conductor takes the form of a strip; and to impartflexibility to it, it may be formed by flattening a length of braidedconducting wire.

The other conductor may be of braided wire of circular cross section; orit may consist of two or more parallel braided wire conductors ofsegmental cross section.

By making the resistance of the line conductor less than that of theother conductor, the latter may be used virtually as the heatingconductor, and the line conductor as virtually a return conductor only.On the other hand, if desired, the line conductor may be of suchresistance relatively to the other conductor that it also dissipatessome heat.

In order to reduce to a minimum the risk of break-down in theinsulation, the line conductor is made as a separate insulated conductoraccording to well-known methods of manufacturing insulated cables, andsubsequently bonded to the Wall of the hose, preferably during themanufacture of the latter. As the separate line conductor can be testedfor faults prior to its application to the hose, the likelihood ofinsulation faults subsequently arising is reduced to an absoluteminimum.

In use for spraying viscous material from a spraying gun, if thematerial to be heated does not require the air to be heated, the ends ofthe two conductors adjacent the gun are joined preferably through thegun, and their other ends connected across the low voltage secondaryWinding of the step-down transformer as described in the parentspecification. However, if the air is to be heated as Well as thematerial to be sprayed, the strip conductors of the two hoses are notused, and the two other conductors are electrically connected at theirgun ends, preferably by the gun itself as described in the parentspecification with reference to the use of a heated air hose in additionto the heated material hose.

In the event of the one conductor being in the form of a number ofparallel braided wire conductors of segmental cross section thedifferent conductors are con- 2,801 ,323 Patented July 30, 1957 nectedin series in order to make a suitable heating circuit across thesecondary of the transformer.

The invention will now be described by way of example with reference tothe accompanying drawings in which the line conductor is in the form ofa strip of flattened braided conducting wire.

In the drawings:

Fig. 1 is a cross section of a hose in which the conductor is of braidedwire of circular cross section.

Fig. 2 is a similar view of Fig. 1 in which the other conductor consistsin a number of parallel braided wire conductors of segmental crosssection.

Fig. 3 is a semidiagrammatic arrangement of one application of the hoseaccording to the invention to a spraying gun.

Referring more particularly to Fig. 1, A is the rubber body portion ofthe hose, and B is a braided wire conductor of circular cross sectionembedded in the said body. C is a strip of rubber in which is embedded aflattened strip of braided conducting wire D, which is separate from thebody of the hose, but is bonded to the latter during the manufactureofthe latter.

Fig. 2 is a similarly constructed hose to that of Fig. 1, but with anumber of segmental braided wire conducting strips E, which areconnected in series at their ends to provide a suitable heating circuit,with the braiding D as the return conductor, across the secondary F of astepdown transformer F, the series connexions being shown in dotted andchain lines respectively.

Fig. 3 shows a spraying gun G to the spraying nozzle of which isconnected the heating hose A, its conducting braiding B beingelectrically connected to the body of the gun, to which is alsoconnected the strip braiding D of the strip C. H is the air hose whichis not heated. The other ends of the braidings B and D are connected tothe secondary F of the step-down transformer F, while the other end ofthe hose A is connected to a supply tank G.

With the hose according to the invention, should there be a fault in theinsulation between the two conductors, as the area between the twoconductors is relatively small, the chance of such fault lying in thisarea is relatively small; while by manufacturing the hose as abovedescribed, the likelihood of faulty insulation occurring is also verysmall.

By making the portion of the gun adjacent the passage leading to thespraying jet of metal having an electrical resistance such that thisportion is in the electrical circuit, the heat is generated up to thespraying jet.

I claim:

1. A flexible heating hose, said hose having embedded therein twobraided wire line conductors insulated from each other; one of saidconductors serving as a return conductor and comprising a flattenedbraided conducting wire of a circular cross section and extendinglongitudinally along the wall of the hose; the other conductor servingas a heating conductor; the resistance of the first conductor being lessthan that of the said other conductor; the ends of the two conductorsadjacent one end of the hose being joined together and their other endsadapted to be connected across a source of electric current.

2. A flexible heating hose, said hose having embedded therein twobraided wire line conductors insulated from each other; one of saidconductors serving as a return conductor and being of compactedcross-section and exending longitudinally along the wall of the hose;the other conductor being of braided wire of circular crosssection andserving as a heating conductor; the resistance of the first conductorbeing less than that of the said other conductor; the ends of the twoconductors adjacent one end of the hose being joined together and theirother ends adapted to be connected across a source of electric current.

3. A flexible heating hose, said hose having embedded therein twobraided wire line conductors insulated from each other; one of saidconductors serving as a return conductor and being of compactedcross-section and extending longitudinally along the wall of the hose;the other conductor comprising a plurality of parallel braided wireconductors of segmental cross-section and serving as a heatingconductor; the resistance of the first conductor being less than that ofthe said other conductor; the ends of the two conductors adjacent oneend of the hose being joined together and their other ends adapted to beconnected across a source of electric current.

4. A flexible heating hose, said hose having embedded therein twobraided wire line conductors insulated from each other; one of saidconductors serving as a return conductor and being of compactedcross-section and extending longitudinally along the wall of the hose;the other conductor comprising a plurality of parallel braided wireconductors of segmental cross-section connected in series and serving asa heating conductor; the resistance of the first conductor being lessthan that of the said other conductor; the ends of the two conductorsadjacent one end of the hose being joined together and their other endsadapted to be connected across a source of electric current.

5. A flexible heating hose, said hose having embedded therein twobraided wire line conductors insulated from References Cited in the fileof this patent UNITED STATES PATENTS 1,252,614 Pieper Jan. 8, 19101,809,714 Mathews June 9, 1931 1,905,343 Carpenter Apr. 25, 19332,274,839 Marick Mar. 3, 1942 2,516,864 Gilmore Aug. 1, 1950 2,526,405Peep Oct. 17, 1950 2,652,093 Burton Sept. 15, 1953 2,657,097 New Oct.27, 1953

